Fibrous unit



Sept., E2, i950 P. H. LANG 2,521,984

FIBROUS UNIT Filed May 19, 1947 /fu @M ZV- BY/wy Patented Slept. 12, V1956 l FiBRoUs UNIT; I

Philip H- Lallg, Summit, N. J assigner to Amen.

.ican Felt Company, Boston, Mass., `a=-corpora, .Y

tion of Massachusetts 1 Application May 19, 1947seris'1 N. 74s,9s3' *l 11 Claims.

-This invention comprises a new-and improved fibrous unit having the advantages of many uses of high eiiciency as well asvbeing adapted for manufacture by automatic machinery atea rapid rateand at low cost.

*I have discovered that al relatively thick battv ofV mixed fibres such as are commonly used in the production of felt, loosely associated but not com'- pletely fulled or hardenedpis highly effective as a lter of aerosols and other uses. I have, moreover, beensuccessful in solving the problem of Y incorporating such a loose batt into a self-sustaining unit in'which the construction of the loose batt ispreserved whilethe unit as a wholel may be conveniently stored, distributed and sembled in its operative position. -v

-One important field of use for the unit of my invention is as a lter for use in-vacuum'clean- 1 position beneath thelfifing die,y

unified by heat and pressure so that they form a thin peripheral rim which is resilient and retains its shape permanently, while the enclosed bres remain as a iluify, relatively thick batt surrounded by the said rim. In the construction described it will be seen that many of the individual fibres, both fusible and non-fusible, extend from the loose batt into the relatively hard compact rim, and thus the soft, thick, center portion of the unit is permanently united and anchored to the rim by which it is supported and sustained.

The present invention also includes within its scope the process herein shown of producing the fibrous unit of my invention. This is characterized by subjecting an annular zone of the batt to pressure between two surfaces compressing said zone of the batt and forming it into a relatively thin rim and to a bonding treatment to permanently maintain the rim, and then severing the portion of the batt disposed exteriorly of the rim. Thus the unit is produced rapidly and at practically a single operation by merely presenting following description of several preferred embodiments thereof, selected for purposes of illustration and shown in the accompanying drawings in which:

cotton withv rffthermoplastic cellulose' acetate A fibres, carding. the` blendedfibres into a batt V'I igsrl andZf'are views in elevation, partly in section-showinga battbeing operated upon'by" a-ringjshaped'fdie,` Eigf'is aplan view of a completed filter unit i' made 'by the process; i Figii is a view, similar to Fig. 2, showing coi-1' operativejring dies operating to form a vdouble- 2 faced iter'unit,""" Fig.l is a" fragmentary view in cross-sectio ofainultieplyllter:unit, f Y F1a-6 is a ske-view' view of thev unit Shown m i Figfi'l Ais a View, "similar to ',Fi'g. 1, showing a batt'with anunderlying ply of felt in operative! position'` beneath a'fring die," ,s

'Fig,"8'is asimilar view showing abatt with an' interpo'sedply 'of' fabric'or 'paper inoperative j'rigsjegic," 1'1 and 1'2 are' fragmentary views in cross-section showing fibrous units of different ply l constructions'and l 4 s `Frag". -1,3 isa viensimiiar to Fig. 2, showing'ajj pl`te,n with a shallowv ring die adapted slightly; te'c'cmpress this bodyportion of the unit. `i

The Compositicil'of'the batt offers awide rangei of choice Mitalieunit is designed for use asfau mier inar-a111111112 111ea1113t1e batt 'may beamed, bypicking andblending approximatelyb Ind almanner similanto thatpractisd in the manuy, factureof felt, but carrying thebatt only through I, the cardine stage and vleaving it in a soft, fluffy,

35,loosely compacted condition approximately 1/'2`ll 111011111 `ov'elralllsl1Cl11es$1 111 Fie'- 1 Such abatt; I0 sshown as supportedfupon the platen II of" a press. y Verticallyimovzable above the platen` I I isa plunger or` top platenA I2 provided with..\a hea-tingunitj andcarrying a ring die I4 having I a-shoulderedendiace .surrounded by a proiectx,=` circumferentialouttingflange I5. The lterunit, is formedgfrom the batt Iil in a single stroke of the upper platen I2 with the ring die vI4. As these. f,

elements are forced downwardly, the batt I'misn,

compactedjandcompressed in an annular rimy I6 and by theactionof-heat andpressure the th,er .4 moplastic, fibres. caught beneath theiiat end face, ofthe ringfgdie `are-,fused and made to coalescel A, thereby unifying all the, fibres in'this zone into,v a thin, relatively hard,resilient rim I6 of substane tial=iwidth, for example; one-eighth or one-quarter,1 inch. jfThe body i1, of Afibresdisposed within rim .I6 I'remain substantially. uneifected and con-.M stitute a..relatively-1so ft, uffy I.center portion adapted to perform the filtering operation of the unit.

The single ring die shown in Figs. 1 and 2 produces a filter flat on the face engaged by the platen II and somewhat convex or dome shaped at its other face. In Fig. 4 I have illustrated a double ring die adapted to produce a filter dome shaped at both faces. This die -is like that shown in Figs. land y2 except that a ring I8 is mounted on the platen II opposite to the ring I4. The opposite face portions 20 and 22 of the batt are uncompressed and form the two domes of the filter within the compressed rim 2l, as shown in Fig. 6. A double dome filter of this nature can also be made by cementing together at their rims I6 two filters Il as illustrated in Fig. 5.

In Fig. 7 I have illustrated the making of the filter shown in Fig. 9 and comprising a fabric base 24 of felt or the like bonded tothe vfilter body 26 at the marginal rim 25. The batt IIJ and fabric 24 are placed on the platen II and the lter is formed by one stroke of the top platen i2 in the manner illustrated in Fig. -2. The fabric can also in like manner be applied to the ltop face of 'the iilter if desired and the filter body 29 will in that case be entirely enclosed within bottom and top fabric covers 28 and 30 as illustrated in Fig. l0. The fabric 24 is bonded `to the rim 25 of the body 26 by any suitable method such as incorporating a bonding fibre or element into the fabric or applying an adhesive orthe like thereto.

I have found that the `filter can be produced with a less abrupt break between the fused edge and the dome shaped portion by employing a suitable separator of fabric or paper between the die and the batt in the forming operation, and in "8 I have illustrated such a separator 21 so disposed. When the die descends the separator acts as a surface cushion between the die and batt and produces the product shown in'Fig. 11 and comprising a dome 32 merging more gently into the fused edge 33. It will 'be understood that the separator will be of a composition treated to cooperate with but not adhere to the product.

The body portion of the lter thus farv described is loose, fluffy and wholly uncompressed and is adapted to function with high porosity and permeability. It may be desirable in some cases to yproduce a filter or the like of more compact composition and having decreased porosity and permeability, as the Vlter illustrated in Fig. 12. In Fig. 13 I have illustrated the formation of 'such'a filter by 'employing a relatively shallow ring die 36. When the die descends the batt I within the annular `zone of the die is engaged by the top platen I2 and slightly compressed simultaneously with the compressing vof the lbatt at said zone. The resulting product is -a filter having a somewhat compressed dome with a fiat top surface 34 merginginto the fused edge 35.

VIt will be apparent that 'the blend lof fibres employed will depend upon the function desired of the product and that the shape of the product can be varied to meet requirements. The composition of the batt can be wool, rayon, ramie,

silk and other natural or artificial fibres either alone or in combination with each other, -and in the preferred form of the invention 5% or more of a suitable thermoplastic fibre is added to effect fusing under heat to form the retaining rim I6. For example, the forming of a filter suitable to be employed for vacuum ,cleaner use will utilize a batt constructed by blending 80% of India scribed in detail certain illustrative embodiments.k

cotton with 20% of thermoplastic cellulose acetate fibres as heretofore described. The lters will be formed from the batt merely by the dieing operation herein illustrated and described.

The filters shown in Figs. 9 and 10, having one or more cover layers of felt, flannel or the like at one or both faces, are employed under conditions where it is necessary to provide a filter having an open and porous batt-like face with a reenforcing secondary filter to strengthen the unit and screen out the ne particles which are not trapped by the primary lter.

The weight and thickness of the batt before pressing can be varied to obtain a soft or hard fused edge, a thick or thin product, or one of different density, porosity, and permeability. The porosity,` permeability andv shape of the product can' also be varied by somewhat compressing` the inner filter portion as illustrated in Fig. 13. The filter as thus formed has increased dust Vretention efficiency and decreased porosity and permeability.

-In Fig. 1 `it is suggested that the platen I2 be heated by an electrical heating unit I3 and such construction is satisfactory. Alternatively one or yboth platens may .be steam heated and under those circumstances a convenient cycle has been found to be `a thirty second cycle including five seconds for pressing and cutting at 300 F. and ytwenty-five seconds for opening and closing.

The design of the lower pressing plate is such that the fused 4edge portion is elevated-above the plate so that the unused portion of the batt is` not pressed and may be recarded thus reducing ywaste to a minimum. Further, instead of using an integral pressing and cutting die as shown in Figs. 1 and 2 vasteel ribbon die may be secured to the circumference of the ring-pressing portion of the die.

I-t has been found desirable in some instances to include in the filter a fabricated reinforcing member, forexample, a sheet ofscreen wire. In such instance two carded batts can be run into the press simultaneously with the Screen wire between-them and the three elements pressed and fused into a single filter unit.

While I lhave herein more specifically illustra'ted'and described the production of lter units employing a minor percentage of thermoplastic fibres :adapted lto heat seal 'the marginal portion of the product at It to produce a retaining ring,

it 'will be understood that the invention is applicable to the production of other fibrous units as'gfor example, air conditioning filters, oil filters, auto filters, powder puiis, cosmetic padding devices, etc. with or without the thermoplastic fibres. The subjecting of an annular zone of the batt to pressure between two surfaces determines the marginal border of the product'and effects the bonding of the fibres in the compressed zone to form permanently the retaining ring, and the severing of the outside .portion of the batt from the ring completes the product. When ino thermoplastic fibres are employed the bonding will be Aeffected by suitable adhesives applied to te-zone to be compressed prior to the dieing operation, or by such other method as is found suitable and effective.

'-Ihe process herein disclosed is the subjectmatter of co-'pending application Ser. lo. 49,524, filed September 16,1948, by applicant jointly with Williaml H. Lehmberg and Charles ivi. Foggett.

Having thus disclosed my invention and dethereof, I claim as new and desire to secure by Letters Patent:

1. A fibrous unit comprising a heterogeneous body containing intermingled fusible and non- .fusible fibres, the said fibres being compacted and unied by coalescence of the fusible libres in a thin fiat peripheral rim which is resilient and retains its shape permanently, and being present in the central area of the unit as a uiy relatively thick batt surrounded by the said rim.

2. A fibrous unit comprising a heterogeneous body containing intermingled thermoplastic and non-thermoplastic fibres, the said fibres being compacted and the thermoplastic fibres unified by coalescence in a thin, fiat, relatively hard peripheral rim, and being present within the inner boundary of said rim in a thick, relatively soft batt, certain bres extending from the soft central batt into the harder peripheral rim.

3. A fibrous unit comprising a body containing intermingled fusible and non-fusible fibres and embodying a central area which is relatively soft, thick and pervious to the passage of air and a peripheral zone which is relatively hard, thin and impervious to air and in which the fusible fibres are unified and coalesced in permanent compacted condition.

4. A fibrous unit as described in claim 3, in which one face surface of the unit has a, fabric cover thereover bonded to the unit at said peripheral Zone.

5. A fibrous unit as described in claim 3, in which both face surfaces of the unit have fabric covers thereover bonded to the unit at said peripheral zone.

6. A fibrous unit comprising a body containing intermingled fusible and non-fusible fibres, the mixed fibres forming a central area which is relatively soft, thick and pervious to the passage of air, and said central area merging into a unitary peripheral rim which is relatively hard, thin and impervious to the passage of air and in which the libres are compacted and held in shape by coalescence of the fusible fibres.

7. A fibrous unit comprising two bodies in face to face contact and each containing intermingled fusible and non-fusible fibres forming a central area which is relatively thick and soft and a multi-ply peripheral rim integral with the bodies and relatively hard and in which the bres are held compacted by coalescence of the fusible fibres, the plies of the rim being adhesively united.

8. A fibrous unit comprising a body containing intermingled fusible and non-fusible fibres, the said fibres forming a central area which is i 6 relatively thick and soft, and in which the fusible fibres are substantially free of coalescence, and being compacted and coalesced into a flat relatively stiff thin rim about said area which renders the unit self-contained and self-sustaining, and a fabric cover on at least one face of the unit.

9.` A fibrous unit comprising thermoplastic and j non-thermoplastic fibres mixed heterogeneously and compacted and fused into a relatively hard peripheral rim surrounding a relatively soft and substantially thicker center portion in which the fusible bres are substantially free of coalescence, and a sheet of fabric heat bonded to the said peripheral rim and covering at least one face of the unit.

l0. A filter unit comprising an intermediate, foraminous reinforcing sheet having upon each of its sides a relatively thick, fluffy batt of fusible and non-fusible fibres intermingled throughout the bodyr of the batt and surrounded by a marginal and relatively thin peripheral rim integral with the batts and comprising the marginal portion of the batts in which the fusible fibres are substantially free of coalescence compressed and bonded into a relatively thin retaining ring.

11. A fibrous unit comprising a relatively thick and uiiy batt of fusible and non-fusible fibres intermingled heterogeneously throughout the body of the batt, a fabricated reinforcing sheet intimately associated with the fibres in the batt, and a marginal and relatively thin peripheral rim integral with the batt and supporting the margin of the reinforcing sheet, said rim comprising the marginal portion of the batt in which the fusible fibres are compressed and bonded by heat into a relatively thin retaining ring.

PHILIP I-I. LANG.

REFERENCES CITED rlhe following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,801,949 Broudy et a1 Apr. 21, 1931 1,821,824 Woodward Sept. 1, 1931 2,022,249 Lofgren Nov. 26, 1935 2,035,097 Schwartz Mar. 24, 1936 2,062,834 Schwartz Dec. 1, 1936 2,147,792 Knight Feb. 21, 1939 2,159,121 Alley May 23, 1939 2,232,640 Schwartzman Feb. 18, 1941 2,264,829 Cover Dec. 2, 1941 2,389,435 Karlstroin Nov. 20, 1945 2,433,531 Ryan Dec. 30', 1947 2,438,771 Topjian Mar. 30, 1948 

1. A FIBROUS UNIT COMPRISING A HETEROGENEOUS BODY CONTAINING INTERMINGLED FUSIBLE AND NONFUSIBLE FIBRES, THE SAID FIBRES BEING COMPACTED AND UNIFIED BY COALESCENCE OF THE FUSIBLE FIBRES IN A THIN FLAT PERIPHERAL RIM WHICH IS RESILIENT AND RETAINS ITS SHAPE PERMANENTLY, AND BEING PRESENT IN THE CENTRAL AREA OF THE UNIT AS A FLUFFY RELATIVELY THICK BATT SURROUNDED BY THE SAID RIM. 